Use of perfluorocarbon (Fluorinert) to enhance reporter gene expression following intratracheal instillation into the lungs of Balb/c mice: Implications for nebulized delivery of plasmids

Perfluorocarbons combine high respiratory gas dissolving capabilities with extreme chemical and biological inertness and therefore offer an attractive option as an excipient in the area of pulmonary therapeutics. Perfluorocar bons have also been shown to 'float' mucus, because of their high densities (1.9-2.5 g/mL), which may hold potential in gene delivery for cystic fibro sis patients, in terms of enhancing penetration through highly viscous mucu s and thereby providing access to target epithelial cells to correct the ge ne defect. Additionally, their low surface tension allows for better disper sion. A commonly available perflurocarbon, heptacosafluorotributylamine (Fl uorinert), was used to deliver either plasmid DNA (pDNA) alone or cationic- lipid-complexed plasmid DNA to the lungs of Balb/c mice by direct intratrac heal instillation. The complexes consisted of supercoiled (SC) plasmid DNA (4.7 Kb, 0.625 mg/mL) and lipid (ethyldimyristoyl phosphatidylcholine [EDMP C]/cholesterol [1:1 mole ratio], with pDNA (3:1 mg pDNA/mM EDMPC in 20 mM T ris-HCl pH 8.0) expressing chloramphenicol acetyl transferase (CAT) or beta -galactosidase (beta -Gal). pDNA alone was supplemented with 14% w/v Fluor inert. Cationic lipid/pDNA complexes were supplemented with 3, 8, and 14% w /v Fluorinert. Results showed that the CAT expression from pDNA alone was e nhanced 24 x using 14% w/v Fluorinert, whereas that from the cationic-lipid -formulated pDNA was enhanced 7 x using 14% w/v Fluorinert. Immunohistochem istry showed that beta -Gal expression was primarily from epithelial cells and not from F4/80 or MAC3 antigen-stained cells (predominantly macrophages ), indicating efficient delivery. (C) 2001 Wiley-Liss, Inc. and the America n Pharmaceutical Association.